The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/imgact_shell.c

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    1 /*-
    2  * Copyright (c) 1993, David Greenman
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/sysproto.h>
   33 #include <sys/exec.h>
   34 #include <sys/imgact.h>
   35 #include <sys/kernel.h>
   36 
   37 #if BYTE_ORDER == LITTLE_ENDIAN
   38 #define SHELLMAGIC      0x2123 /* #! */
   39 #else
   40 #define SHELLMAGIC      0x2321
   41 #endif
   42 
   43 /*
   44  * Shell interpreter image activator. An interpreter name beginning
   45  *      at imgp->stringbase is the minimal successful exit requirement.
   46  */
   47 int
   48 exec_shell_imgact(imgp)
   49         struct image_params *imgp;
   50 {
   51         const char *image_header = imgp->image_header;
   52         const char *ihp, *line_endp;
   53         char *interp;
   54 
   55         /* a shell script? */
   56         if (((const short *) image_header)[0] != SHELLMAGIC)
   57                 return(-1);
   58 
   59         /*
   60          * Don't allow a shell script to be the shell for a shell
   61          *      script. :-)
   62          */
   63         if (imgp->interpreted)
   64                 return(ENOEXEC);
   65 
   66         imgp->interpreted = 1;
   67 
   68         /*
   69          * Copy shell name and arguments from image_header into string
   70          *      buffer.
   71          */
   72 
   73         /*
   74          * Find end of line; return if the line > MAXSHELLCMDLEN long.
   75          */
   76 #define REL4_SCRIPT_OPTIONS  1
   77 #if REL4_SCRIPT_OPTIONS
   78         /*
   79          * XXX - This behavior is not correct, but it matches what FreeBSD
   80          * has being doing since March 2000 (3.5-release, and all of the
   81          * 4.x releases), so we will continue to go with it for 5.4-release.
   82          * This behavior will certainly be changed before 6.0-release, and
   83          * might change for 5.5-release.
   84          */ 
   85         for (ihp = &image_header[2]; *ihp != '\n' && *ihp != '#'; ++ihp) {
   86 #else
   87         /*
   88          * XXX - This behavior is closer to correct, but it requires a
   89          * change to /bin/sh which is not ready yet, and which will also
   90          * require making another incompatible change here.  We will
   91          * not have all that tested in time for 5.4-release.  But this
   92          * is left here as a compile-time option, because attempting to
   93          * parse-out the comments causes a problem for some users.
   94          */ 
   95         for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
   96 #endif
   97                 if (ihp >= &image_header[MAXSHELLCMDLEN])
   98                         return(ENAMETOOLONG);
   99         }
  100         line_endp = ihp;
  101 
  102         /* reset for another pass */
  103         ihp = &image_header[2];
  104 
  105         /* Skip over leading spaces - until the interpreter name */
  106         while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
  107 
  108         /* copy the interpreter name */
  109         interp = imgp->interpreter_name;
  110         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
  111                 *interp++ = *ihp++;
  112         *interp = '\0';
  113 
  114         /* Disallow a null interpreter filename */
  115         if (*imgp->interpreter_name == '\0')
  116                 return(ENOEXEC);
  117 
  118         /* reset for another pass */
  119         ihp = &image_header[2];
  120 
  121         /* copy the interpreter name and arguments */
  122         while (ihp < line_endp) {
  123                 /* Skip over leading spaces */
  124                 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
  125 
  126                 if (ihp < line_endp) {
  127                         /*
  128                          * Copy to end of token. No need to watch stringspace
  129                          *      because this is at the front of the string buffer
  130                          *      and the maximum shell command length is tiny.
  131                          */
  132                         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
  133                                 *imgp->stringp++ = *ihp++;
  134                                 imgp->stringspace--;
  135                         }
  136 
  137                         *imgp->stringp++ = 0;
  138                         imgp->stringspace--;
  139 
  140                         imgp->argc++;
  141                 }
  142         }
  143 
  144         imgp->argv0 = imgp->fname;
  145 
  146         return(0);
  147 }
  148 
  149 /*
  150  * Tell kern_execve.c about it, with a little help from the linker.
  151  */
  152 static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
  153 EXEC_SET(shell, shell_execsw);

Cache object: 979571be1f9cd765eae67f149bd995b3


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